1. Field of the Invention
The present invention generally relates to electronic equipment and, more specifically, to mobile telecommunication devices equipped with a battery. The present invention more specifically applies to such devices capable of establishing, in addition to communications using a mobile telephony network, near-field communications.
2. Discussion of the Related Art
So-called near-field communications are based on small-distance contactless communication protocols between two elements. Such protocols generally use an electromagnetic field generated by one of the elements, called a reader, to supply the other element, called a transponder or card. The remote-supply carrier is also used as a carrier for the communication. Such communication protocols are generally designated by their standard (for example, 14443-A, B JIS, NFC, Forum, ECMA).
Among such protocols, the protocol known as NFC (near field communication) provides for the same communicating module to be able to act either as a contactless reader, or as a contactless card (transponder). According to its operating mode, this dual NFC communication module then exploits the electronic circuits of the device hosting it differently.
The present invention more specifically applies to mobile telecommunication devices capable of supporting the NFC protocol, also known under the references of standards ISO 14443, ECMA 340 and 352, ETSI TS 102 613 (Smart Cards, UICC—Contactless Front-end (CLF) Interface; Part 1: Physical and data link layer characteristics) and ETSI TS 102 622 (Smart Cards UICC—Contactless Front-end (CLF) Interface; Host Controller Interface (HCI)).
In the NFC protocol, the device containing the dual communication device generally is a mobile telecommunication device capable of using a mobile telephony network (of GSM type). For example, it may be a cell phone, a communicating personal digital assistant (PDA), etc.
An aim is to increase the range of application of mobile telephony devices by appending thereto functions which are otherwise reserved to electromagnetic transponders (for example, transport vouchers, electronic purses, etc.). The mobile device then replaces the contactless card used to validate a transaction with a reader (transit control box, electronic purse reader, etc.). The possibility of also communicating over the mobile telephony network enables validating transactions in so-called on-line protocols. Further, the mobile device may also operate as a contactless card reader, for example, to read text data or a URL from a contactless tag supporting the protocols or data formats predefined in the NFC Forum, for example, to recharge a transport voucher or an electronic purse supported by a separate contactless card, by using the telephone network to have the transaction validated, for example, by a bank.
When the device operates in reader mode, its NFC module generates the electromagnetic contactless communication field by drawing the required power from the battery of the mobile device. When the device operates in card mode, its NFC module needs to be able to operate even when the battery of the device is discharged or when the telephone function is deactivated, by extracting the power necessary to its operation from the electromagnetic field generated by the reader.
For simplification, reference will be made hereafter to a cell phone as an example of a mobile telecommunication device.
A specificity of cell phones is to use a subscriber identification module (SIM), generally called SIM card, and especially containing the tools and identifiers required by the mobile telephony operator to access to its network. The SIM card communicates with the telephone processor for purposes of identification and authentication of the mobile telephony subscription.
In a contactless communication protocol, there also is a need for an identification and authentication of the communicating devices.
Cell phones integrating (typically, on the same motherboard) the mobile telephony circuits and contactless communication circuits are known. Such a solution is however reserved to top of the line phones due to the cost increase linked to the NFC module. Further, such phones generally only support the reader mode of the NFC protocol.
The developments of the NFC protocol provide for the same subscriber identification module to be sharable by the phone and its NFC module. This amounts to using the SIM card of the telephone for identification and authentication purposes for the near-field communication. The communication protocol (SWP—Single Wire Protocol) between the SIM card and the NFC module is however different from the protocol (set by an ISO standard 7816) used between the SIM card and the telephone processor. A SIM card supporting at least both protocols, and thus an NFC operation, will be designated as SIM-NFC.
To share the same subscriber identification module (the same SIM card) between the phone and its NFC module, and to support the card mode of the NFC protocol, the SIM-NFC card needs to be able to be powered by the NFC module when the telephone is off (or when its processor is deactivated).
It would be desirable to have a mobile telecommunication device using a network of mobile telephony type, also capable of supporting an operation according to the NFC protocol in card mode and in reader mode, controlled by the subscriber identification module of the mobile device.
It would also be desirable for a user to be able to reversibly transform a mobile telecommunication device to give it near-field communication functions.